Polydopamine-mediated in situ growth of multibranched Au mesocrystals on carbon nanotube foams for sensitive, uniform and stable SERS detection.

A facile, one-pot synthesis method is proposed for the in situ growth of multibranched gold (Au) mesocrystals on polydopamine (PDA)-modified three-dimensional (3D) carbon nanotube (CNT) foams using cetyltrimethylammonium bromide (CTAB) and silver nitrate (AgNO) as shape-directing agents. The synthesized Au mesocrystals exhibit complex 3D architectures composed of ultra-long branches (exceeding 1 μm) with sharp tips and serrated edges. Their morphology can be precisely tuned on CNT foams by adjusting the concentrations of CTAB and AgNO in the growth solutions. The resulting CNT foam-multibranched Au mesocrystal hybrids exhibit high surface-enhanced Raman scattering (SERS) sensitivity, enabling the detection of rhodamine 6G and thiram at concentrations as low as 1 × 10 M and 1 × 10 M, respectively. Additionally, the 3D SERS substrates exhibit excellent uniformity, reproducibility, and long-term stability, maintaining high SERS activity after 10 weeks of storage. Importantly, the SERS substrates achieve sensitive detection of thiram on apple peels down to 2.4 ng/cm. This work provides a promising strategy for the efficient fabrication of high-performance 3D SERS platforms for practical sensing applications.